Smart Urban Planning Support through Web Data Science on Open and Enterprise Data

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  Prediction of expensive datasets starting from a set of cheap heterogeneous information sources in smart city scenarios. Prediction of the population and land use of Milano starting from data about Points Of Interest and phone activity.
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  • 1. Smart Urban Planning Support through Web Data Science on Open and Enterprise Data Gloria Re Calegari and Irene Celino CEFRIEL – Politecnico di Milano 1 The 24th International World Wide Web Conference Florence, Italy 18 – 22 May 2015 Web Data Science meets Smart Cities 19th May 2015
  • 2. Digital information about cities • Large number of data sources available on the web (Open data): • Urban planning (land cover, public registers) • Demographics and statistics about municipality • User generated information: • Volunteered geographic information and crowdsourcing information (Open Street Map) • Location based social network (Foursquare check-ins and geo located information) • Close data sources produced and maintained by enterprises: • Phone activity data Cost of data management (collection, cleansing, maintenance) is highly variable with respect to the diverse data origins. 2
  • 3. Research goal Long term goal: • Can we predict (generate or update) a costly dataset from a set of cheap information sources? Cheap datasets Expensive datasets Predict or update 3
  • 4. Our case study • Data collection • Available datasets about Milano • Problem of spatial granularities and pre-processing of the datasets • Data processing • Definition of input/output • Predictive analysis • Statistical learning • Machine learning • Results evaluation 4
  • 5. Milano datasets Demographics: • population density • Spatial resolution: census area • Source: Milano open data Points of interest (POIs): • Trasports, schools, sports facilities, amenity places, shops ... • Spatial resolution: lat-long points • Source: Milano open data (official) and Open Street Map (user generated) 5
  • 6. Milano datasets Land use cover: • type of land use according to CORINE taxonomy (3-levels hierarchy, up to 40 types of land use defined) • CORINE taxonomy • 5 type selected (which better feature metropolitan area as Milan) 1. Residential 2. Agricultural 3. Commercial/industrial 4. Parks and green areas 5. Sport centres • Spatial resolution: building level • Source: Lombardy region open data 6
  • 7. Milano datasets Call data records: • 5 phone activities • Incoming SMS • Outcoming SMS • Incoming CALL • Outcoming CALL • Internet • Recorded every 10 minutes (144 values a day for each activity) for 2 months (Nov-Dec 2013) • Summarizing structure: a footprint for each cell (average activity over all the days, distinguishing between week and weekend days) • Spatial resolution: grid of 3538 square cells of 250m • Source: Telecom Italia – provided for their Big Data Challenge 7
  • 8. Pre-processing Uniform the spatial resolution in order to make datasets comparable. Spatial resolution used: grid of 3538 square cells of 250m Overlapping and intersecting layers using QGIS software. New datasets generated: • Presence/absence of POIs in each cell • Weighted sum of population density in each cell • Percentage shares of each land use over each cell area 8
  • 9. Selection of input/output variables Predictive models (regression) Land use density: • Residential • Agricultural • Commercial • Green area • Sport facilities Population density Telecom data • means of each phone activity (10 values) • means hour-by- hour of all the activities (24 values) POIs • School • Transport • Shop • Food • Sport • ... 9 INPUT OUTPUT
  • 10. Aims of the experiments 1. Comparing different regression algorithms 1. Statistical Learning approach -> Multiple Linear Regression (MLR) 2. Machine Learning approach -> Random Forest (RF) 2. Evaluating how the number of predictors impacts the models performances 1. All the predictors 2. Manual selection of a subset of predictors 3. Automatic selection of predictors by AIC (Akaike information criterion) 10
  • 11. Tests performed 5 tests combining the different algorithms and inputs All predictors Manual selection AIC selection RF x x MLR x x x 11
  • 12. Methodology of the experiments • Dividing dataset into training (90%) and test (10%) sets • Training the model using the 10 fold cross validation to avoid overfitting • Calculating the Adjusted R^2 Index to measure the goodness of the model (percentage of variance explained) 12
  • 13. Results 1) Different output results: some variables are predicted better 2) Models comparison: RF always equals or outperforms MLR (data does not follow a linear distribution but a more complex one) 3) Number of predictors: RF-manual selection is usually better than RF- all and MLR AIC-selection is better than others MLR models. Higher the number of variables included in the model, the more the risk of overfitting (higher difference between R^2 of training and test set) MLR – manual selection MLR – all MLR – AIC selection RF – all RF– manual selection 13 Adj R-square RF - all RF - manual selection Train Test Train Test population 0.668 0.623 0.604 0.591 residential 0.633 0.588 0.623 0.614
  • 14. worse results in RF-manual selection Predictors importance calculated by RF-all 14 7 vars in the top10 out of the manually selected 2 vars in the top10 out of the manually selected Variable selection is an essential step in optimizing a predictive model better results in RF-manual selection
  • 15. Conclusions • Encouraging results in employing open and enterprise datasets in regression models • Good results in predicting population, residential and agricultural areas -> explained variability reaching 62% • There is a relation between land use/popoulation and diverse and heterogeneous datasets used as predictors (POIs and phone activity) • Chosing the best predictors is an ‘’art’’. A lot of relevant data available about cities. A preprocessing phase is essential to select only the most informative and discriminative variables. 15
  • 16. Future work • Improvements on input variables: preprocessing predictors to extract more discriminative information from the data (changing the POIs data from presence/absence to distances from the closest POI ) • Improvements on output variables: definition of new outputs that are easier to predict experimentally (dense residential, sparse residential, agricultural, industrial/commercial, parks and natural stuff). Problems in predicting specific land uses (parks, sport centres) -> other kind of input data may be required. • Improvements on predictive algorithms: better results using Support Vector Machine (SVM) -> the urban environment is so complex that cannot be modelled using linear models • Reproducibility of our solution on different scenarios: comparable results obtained on other European cities (Barcelona, Muenchen and Brussels) -> the methodology proposed is successful. 16
  • 17. 17 Thank you! Any question? Gloria Re Calegari and Irene Celino CEFRIEL – Politecnico di Milano
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